(190l) Reverse-Engineering Calcium Signaling in a Developing Organ

Organ development depends on cell-based sensing to tightly couple biochemical and mechanical cues. Signals are transduced to regulate cell processes through key integrators such as calcium (Ca²⁺) ions. However, how Ca²⁺ signaling contributes to organogenesis is poorly understood. Very few tools exist to study cell signaling at millimeter length scales. Here, I will present collaborative efforts to advance organ-level experimentation and quantitative analysis methods. We developed a fluidic device called the Regulated Epithelial Microenvironment Chip to modulate multiple stimuli acting on micro-organs. As a specific demonstration, we are using advanced genetic tools available in a fruit fly-based model of organ growth, the larval wing imaginal disc, to quantitatively study the regulation and function of Ca²⁺ signaling dynamics occurring during organ growth in vivo. The system also enables live imaging of cell signaling responses. This approach enabled us to decouple the contributions of biochemical signaling and mechanical loading to Ca²⁺ signaling dynamics. We discovered that stimulation of intercellular calcium waves (ICWs) depend upon the pre-loading signaling activity, rather than the magnitude or duration of mechanical loading. Intercellular calcium signaling relies on calcium induced calcium release and propagation through gap junctions. These results provide evidence for a “Mechanical Stress Dissipation” hypothesis of Ca²⁺ signaling. This hypothesis states that intercellular Ca²⁺ transients provide a readout of growth and contribute to the regulation of adhesion and actomyosin contractility as the tissue grows. These studies help identify strategies for spatiotemporally encoding information through Ca²⁺ signaling within the multicellular context. Ultimately, advances in calcium signaling engineering can lead to novel approaches to detect a broad range of stimuli, target cancer, and accelerate tissue regeneration.